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Matlab/Octave

Matlab/Octave. The function lu(A) completes the LU factorization only for a square matrix A, and returns a lower triangular matrix $ L$, an upper triangular matrix $ U$, and a (permutation) matrix $ P$. Since it returns three matrices at once, the returned matrices must be specified as in the following form:
> [L, U, P] = lu(A)

EXAMPLE 1. Find an LU factorization of $ U = \begin{bmatrix} 1 & 4 &-1 & 5 \\ 3 & 7 &-2 & 9 \\ -2 &-3 & 1 &-4 \\ -1 & 6 &-1 & 7 \end{bmatrix}$

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